Electrical arc ignition in narrow slots: high-voltage generation

A narrow-slot fuse can be used to commutate current to a parallel connected varistor for which a high fuse arc power is required. During the voltage rise two characteristic periods are observed. The first is dominated by the fuse element decomposition process, and the second by axial flow development and metal vapours removal. In the first period the energy accumulation in the arc column is of importance. It is influenced by a radial mass shift and very high pressure of the fuse element vapours. In that time, the axial gas-flow is negligible. Relations between fuse dimensions, plasma parameters and the ignition voltage rate of rise are presented. The fuse element surface evaporation, its deformation and the arc length development have been considered